The present invention relates to magnetic recording/playback heads having superconductor shields for spatially directing magnetic fields used in recording and playback operations.
a. Magnetic Heads
Magnetic heads are in wide use for the recording and/or playing back of analog or digital data stored on magnetic recording medium such as tapes or disks. Prior art recording heads typically consist of a ferromagnetic core defining a magnetic flux path which is closed except for a gap. A conductor such as a coil is electromagnetically coupled to the core. In recording, a current is passed through the conductor to produce the flux in the core and to produce a fringing field at the gap which impinges a portion of the magnetic medium immediately adjacent the gap. The fringing field locally magnetizes the medium. In playback, a magnetized region of the medium moving past the gap causes a flux change in the core. This flux change induces a current in the conductor which provides a data signal.
b. Superconductors Used In Magnetic Devices
It is known in the prior art that superconductors can exhibit useful magnetic shielding properties. For example, U.S. Pat. No. 3,361,940 to Culver et al. discloses a technique for providing a superconductive magnetic shield devoid of substantially trapped magnetic flux. The effect of superconductors on magnetic flux have been modeled and techniques of magnetic flux compression based on such models have been proposed. See Swartz et al. "Characteristics And A New Application Of High-Field Superconductors", J. App. Phys. Vol. 33, No. 7 (July 1962).
In the area of magnetic head design, it has been generally proposed to improve the recording and reproducing characteristics of a low temperature magnetic head by forming a gap spacer of a superconductor material between head halves. See Japanese Patent Document No. 60-154315(A) to Ogawa (Sanyo Denki K.K.)
c. Objects
It is desirable to provide magnetic heads which are capable of concentrating a greater amount of magnetic flux in a smaller region of the magnetic medium. In this way each sequential bit of recorded data will occupy less of the magnetic medium and data tracks can be placed closer to one another. In recording, as data density increases (e.g. to above 15,000 flux reversals/inch) the allowable spread of the magnetic field decreases. In playback, a smaller magnetized region of the recording medium must suffice to produce a detectable electrical signal from the head.
The application and detection of magnetic flux in small regions is achievable, in part, by reducing the size of the track width and gap of a conventional recording head. However, unless great care is given to the geometric design of the core, the fringing field can spread along the core thereby degrading performance. Moreover, reductions in size of the core can lead to significant manufacturing difficulties in achieving the required dimensional tolerances and durability. In spite of these efforts, the magnetic flux produced by such heads may be insufficiently focused to produce the desired density of data storage.
Accordingly, it is an object of the present invention to provide magnetic head structures for concentrating magnetic flux used in playback and recording.
It is another object of the present invention to increase magnetic record/playback head efficiency.
It is another object of the present invention to provide head structures for concentrating magnetic flux, which are readily manufacturable.
It is another object of the present invention to provide magnetic head structures which are more durable.
These and other objects and features will be apparent from a review of the written description and drawings of this patent document.